U.S. patent number 4,103,678 [Application Number 05/789,713] was granted by the patent office on 1978-08-01 for nocturnal penile tumescense monitor.
This patent grant is currently assigned to American Medical Systems, Inc.. Invention is credited to Ismet Karacan, Larry G. Paulson, Gerald W. Timm.
United States Patent |
4,103,678 |
Karacan , et al. |
August 1, 1978 |
Nocturnal penile tumescense monitor
Abstract
Apparatus for generating and recording signals from two separate
sensors on a patient adapted to provide an indication of the
condition of an anatomical member to be monitored. A control
cabinet having an integral strip chart recorder is provided with
plug in inputs for two externally connected strain gauges. Each
strain gauge makes up one leg of a bridge circuit. The bridge
outputs are amplified and multiplexed into a single channel strip
chart recorder having a single, heated stylus which records two
separate traces based on the signals received from the two sensors.
Heat to the recordinng pen or stylus is turned off during switching
excursions of the pen between the two traces so as to eliminate
shading and marking which would otherwise occur on the recording
chart between the traces at slow chart speeds. In the nocturnal
penile tumescence monitoring application for which the apparaus is
primarily intended, two mercury strain gauges in the form of
elastomer rings are positioned at the base and tip of the penis.
Minute variations in penile size occurring during the Rapid Eye
Movement stages of sleep are sensed by the strain gauges,
amplified, through bridge circuits and recorded in two separate
traces.
Inventors: |
Karacan; Ismet (Houston,
TX), Paulson; Larry G. (Minneapolis, MN), Timm; Gerald
W. (Minneapolis, MN) |
Assignee: |
American Medical Systems, Inc.
(Minneapolis, MN)
|
Family
ID: |
25148466 |
Appl.
No.: |
05/789,713 |
Filed: |
April 21, 1977 |
Current U.S.
Class: |
600/587;
346/33ME; 346/34; 346/62; 346/76.1 |
Current CPC
Class: |
A61B
5/1073 (20130101); A61B 5/227 (20130101); A61B
5/4393 (20130101); A61B 2562/0261 (20130101) |
Current International
Class: |
A61B
5/103 (20060101); A61B 5/22 (20060101); A61B
005/00 (); G01D 015/10 () |
Field of
Search: |
;128/2R,2S,2.5Q,2.5V,2.6G ;346/33ME,34,62,76R ;219/216 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Ray, C. D., "Medical Engineering", Yrbk Pulbishing, Chic., 1974, p.
443. .
Hokanson, et al., "Electrically Calibrated Plethysmograph for
Direct Measurement of Limb Blood Flow", IEEE Trans. on Biomed.
Engr., vol. BME-22, No. 1, Jan. 1975, pp. 25-29..
|
Primary Examiner: Michell; Robert W.
Assistant Examiner: Jaworski; Frank
Attorney, Agent or Firm: Williamson, Bains, Moore &
Hansen
Claims
What is claimed is:
1. Apparatus for simultaneously monitoring electrical signals from
two, separate sensing devices and recording same on a single,
multiplexing strip chart recorder, comprising:
a strip chart recorder comprising:
a movable pen disposed in trace producing relation to heat
sensitive recording paper;
a motor drivingly connected to said pen;
a heater on said pen;
drive means for advancing said recording paper past said pen at a
predetermined speed;
electrical circuit means connecting said pen motor and said pen
heater to a power source and comprising:
switch means interconnected to said pen motor for transmitting
drive signals thereto;
two separate sensing devices connected to said switch means, said
sensing devices being selectively positionable at different
monitoring locations to detect changes in a condition to be
monitored and trigger the generation of signals in response to
same;
control means connected to said switch means and operative to emit
control signals at predetermined time intervals to condition said
switch means to receive input signals alternately from said two
sensing devices at predetermined time intervals, and said switch
means transmitting said input signals alternately from said two
sensing devices to said pen motor, whereby said motor actuates said
pen so as to record two separate traces on said recording paper
corresponding to respective ones of said input signals from said
two sensing devices; and
signal relaying means connected between said control means and said
pen heater and operative to selectively transmit an energizing
signal to said pen heater in response to control signals from said
control means in synchronization with the alternate conditioning of
said switch means, at such frequency that said pen heater is
de-energized during switching excursions of said pen between said
two traces.
2. Apparatus as defined in claim 1 wherein:
said control means comprises a clock oscillator emitting pulse
signals at a predetermined frequency.
3. Apparatus as defined in claim 2 wherein:
said control means further comprises a frequency divider in said
circuit means between said clock oscillator and said switch means,
said frequency divider having an output frequency to said switch
means which is one-half the frequency of input control signals from
said clock oscillator, whereby said frequency divider trips said
switch means to switch between input signals from said two
switching devices on every other pulse signal from said clock
oscillator; and
said signal relaying means operates on basic clock oscillator
frequency and transmits said pulse signals to said pen heater to
cycle the pen heater on and off with every pulse signal from said
clock oscillator, whereby said pen heater is de-energized and cools
down during the last half of each recording interval and switching
movement of said pen between traces occurs after the pen heater has
cooled down, thereby substantially eliminating pen marking between
traces.
4. Apparatus as defined in claim 2 wherein:
said clock oscillator emits said control pulse signals at a
frequency of less than one pulse per one-half second.
5. Apparatus as defined in claim 1 wherein:
said drive means advances said recording paper at a speed less than
fifty centimeters per hour.
6. Apparatus as defined in claim 1 wherein:
said sensing devices comprise elastomer strain gauge rings which
change impedance as they expand and contract with variations in the
circumference of an anatomical member around which they are
positioned.
7. Apparatus as defined in claim 6 wherein:
each of said strain gauges comprises one leg of a separate bridge
circuit; and
separate amplifier means connected in said circuit means to
independently receive output signals from each of said strain
gauges and transmit separate, amplified signals to said switch
means.
8. Apparatus as defined in claim 7 wherein:
one of said amplifier means incorporates bias means effective to
add a predetermined increment to the signal outputted by one of
said bridge circuits to displace the trace of said signal from the
trace of the other signal from the other bridge circuit.
9. Apparatus as defined in claim 6 wherein:
said electrical circuit means comprises warning signal means and
means for actuating same in response to a magnitude of signal
triggered by either one of said strain gauges in comparison with a
normal signal range which indicates a malfunction of said first or
second strain gauge.
10. Apparatus for monitoring and recording nocturnal penile
tumescence comprising:
a movable pen disposed in trace producing relation to heat
sensitive recording paper;
a motor drivingly connected to said pen;
a heater on said pen;
drive means for advancing said recording paper past said pen at a
predetermined speed;
electrical circuit means connecting said pen motor and said pen
heater to a power source;
switch means interconnected to said pen motor in said electrical
circuit means for transmitting drive signals thereto;
a first tumescence responsive strain gauge at one end of a
subject's penis;
first electrical means interconnected between said first strain
gauge and said switch means in said electrical circuit means and
operative to generate a first signal responsive to changes in the
impedance of said first strain gauge caused by variations in penile
tumescence;
a second tumescence responsive strain gauge on the subject's penis
at a longitudinally spaced location from said first strain
gauge;
second electrical means interconnected between said second strain
gauge and said switch means in said electrical circuit means and
operative to generate a second signal responsive to changes in the
impedance of said second strain gauge caused by variations in
penile tumescence at said longitudinally spaced locations; and
control means connected to said switch means and operative to emit
control signals at predetermined time intervals to condition said
switch means to alternatively receive said first and second signals
from said first and second strain gauges at predetermined time
intervals, and said switch means transmitting said first and second
signals alternately to said pen motor, whereby said pen motor
drives said pen to record two separate traces on said recording
paper indicating penile tumescence as sensed by said strain
gauges.
11. Apparatus as defined in claim 10 wherein:
said first and second strain gauges are positioned at the base and
tip of a subject's penis.
12. Apparatus as defined in claim 11 wherein said strain gauges are
mercury filled, elastomer rings.
13. Apparatus as defined in claim 10 wherein:
said electrical circuit means comprises warning signal means and
means for energizing same in response to a magnitude of said first
or second signal in comparison with a normal signal range which
indicates a malfunction of said first or second strain gauge.
14. Apparatus as defined in claim 13 wherein:
said warning signal means comprises first and second warning
indicator devices connected in said electrical circuit and said
energizing means comprises first and second energizing means
connected to each of said warning indicator devices and to said
control means, whereby control signals from said control means are
conducted by said energizing means to energize said first or second
warning indicator device.
15. Apparatus as defined in claim 10 wherein:
said electrical circuit means includes amplifier means in the
circuit of said first electrical means operative to add a
predetermined amplitude increment to said first signal which
provides a positive, visual displacement between said two traces on
said recording papers.
16. Apparatus as defined in claim 10 wherein:
said control means comprises a clock oscillator which regulates
said switch means to cycle between said two signals at a rate
slower than once per half second.
17. Apparatus as defined in claim 10 wherein:
signal relaying means is connected in said electrical circuit means
between said control means and said pen heater and operates to
selectively transmit energizing signals to said pen heater from
said control means in synchronization with the cycling of said
switch means between said first and second signals so as to
de-energize said pen heater during switching excursions of said pen
between said two traces, whereby undesired marking and shading
between said traces will be avoided even at relatively slow chart
speeds.
18. Apparatus as defined in claim 17 wherein:
said drive means advances said recording paper at a speed of less
than fifty centimeters per hour.
19. Apparatus as defined in claim 17 wherein:
said signal relaying means comprises a silicone controlled
rectifier.
Description
BACKGROUND OF THE INVENTION
Recognition that nocturnal penile tumescence monitoring can be of
assistance in diagnosing male erectile impotence has led to the
development of various types of devices and techniques for
conducting such monitoring. In an article entitled "A Simple and
Inexpensive Transducer for Quantitative Measurements of Penile
Erection During Sleep", Behavior Research Methods and
Instrumentation, Volume 1, Pages 251-252, 1969, Ismet Karacan
describes a mercury strain gauge transducer for measuring penile
erection, the transducer being in the form of an elastomer ring. A
number of devices and procedures for monitoring penile tumescence
during sleep are noted and referenced in an article entitled
"Sleep-Related Penile Tumescence as a Function of Age", American
Journal Psychiatry, Volume 132, page 9, September 1975. Strip chart
recording instruments capable of recording two traces from input
signals with a single, heated pen are also known. Such an
instrument is manufactured by Astro-Med, Division of Atlan-Tol
Industries, Inc., West Warwick, Rhode Island.
We have discovered that a particularly clear and objective view of
the part that organic causes play in male erectile impotence can be
achieved by utilizing two strain gauges attached to the base and
tip of the penis. Effective monitoring and recording of tumescence
variations sensed by the two strain gauges is accomplished by a
specially designed strip chart recorder of the single stylus,
multiplexing type.
BRIEF SUMMARY OF THE INVENTION
The monitoring and recording instrument of this invention has been
developed with a view towards providing an accurate means of
obtaining and recording diagnostic data from two separate locations
on a patient over extended recording intervals with minimum
disturbance of the patient and with the generation of manageable
amount of recording chart paper.
These basic objectives have been realized by utilizing a strip
chart recorder capable of recording two traces from two separate
input signals with a single pen or stylus. The heat sensitive
recording paper is advanced past the heated pen at a predetermined
slow speed which provides a meaningful trace record of two input
signals on a minimum amount of recorded paper over relatively long
recording periods of eight hours or more.
The instrument has plug in connections for receiving signals from
two externally located sensing devices. With the primary
anticipated application being the measurement of changes in size of
anatomical members, the sensing devices advantageously take the
form of elastomer strain gauge rings, each of which form one leg of
separate, signal generating bridge circuits. The strain gauges
change impedance as they expand and contract with variations in the
circumference of an anatomical member on which they are mounted. As
a result, the separate bridge circuits generate responsive signals
which are amplified and transmitted to a drive motor for the
recording pen through an analog switch. A controller, preferably in
the form of a clock oscillator, emits control signals which are
transmitted to trip the analog switch to cycle between the two
diagnostic signals at a predetermined frequency.
As a particularly advantageous feature, controls are provided which
operate to cyclically de-energize the pen heater during switching
excursions of the recording pen between the two traces. This
substantially eliminates pen marking and shading between the traces
at relatively slow chart speeds.
The cycling of the pen heater is effectively accomplished by a
signal relaying device, such as an SCR which transmits energizing
signals from the aforesaid clock oscillator to the pen heater at a
predetermined frequency with respect to the cycling frequency of
the analog switch, such that the pen heater is de-energized during
switching movement of the pen between traces on the recording
paper. A frequency divider between the clock oscillator and the
analog switch ensures that the tripping frequency of the analog
switch is so regulated with respect to the rate of pen heater
cycling that the pen heater will be de-energized and cooled down
during the last half of each recording interval. This further
lessens the possibility of pen marking between traces.
Another beneficial aspect of the instrument of this invention
resides in the provision of warning indicators, such as, lights,
which are automatically activated if the strain gauge sensing
devices are broken or improperly connected. This ensures that false
signals will readily be detected thereby avoiding improper
diagnosis.
The instrument and apparatus disclosed herein is particularly
adapted for monitoring nocturnal penile tumescence. It has been
found that a particularly effective diagnosis can be made for
purposes of distinguishing between organic and psychogenic causes
of male erectile impotence by utilizing two tumescence sensitive
strain gauges at longitudinally spaced locations on a subject's
penis. The strain gauges are connected through signal generating
bridge circuits with an analog switch of a strip chart recorder of
the above described construction and operation.
These and other objects and advantages of this invention will
become readily apparent as the following description is read in
conjunction with the accompanying drawings wherein like reference
numerals have been used to designate like elements throughout the
several views.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the recording instrument of this
invention showing the manner of application for nocturnal penile
tumescence monitoring;
FIGS. 2 and 3 are typical, condensed tracings of nocturnal penile
tumescence activity;
FIG. 4 is a block diagram of the monitoring and recording apparatus
of this invention;
FIG. 5 is a schematic, circuit diagram for the recording and
monitoring unit shown in FIG. 1;
FIG. 6 is a diagram of the output circuits from the Wheatstone
bridges to which the strain gauge sensing devices are connected;
and
FIG. 7 is a circuit diagram of the control arrangement utilized for
switching a recording pen between traces and cycling the pen
heater.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, there is shown in FIG. 1, and
schematically in FIG. 4, a preferred embodiment of the recording
instrument of this invention, and its component parts. This
instrument consists of a control cabinet 1 having an integral strip
chart recorder and input connections 2 and 4 for a plug in set of
two externally connected sensing devices. Preferably, for reasons
clarified hereinafter, the sensing devices comprise strain gauges 6
and 8. The cable assemblies 10 and 12 for each strain gauge each
include a pair of lead wires connected as shown to plug in
connections 2 and 4 on the instrument panel. The strip chart
recorder generally indicated by reference numeral 14 utilizes heat
sensitive recording paper 16. A manual advance knob 18 is provided
for loading and positioning recording paper. The single recording
pen or stylus 20 is positioned in trace producing relation to
recording paper 16 in a standard manner and is actuated to produce
two separate traces by a drive motor 22 in response to signals from
the two strain gauges or sensing devices 6 and 8. FIG. 5
illustrates schematically the driving connection between motor 22
and recording pen 20. Pen 20 moves back and forth between the two
traces being recorded on a support bar 21 as shown in FIG. 1.
Chart paper 16 is guided around a support rod and drive roller in a
well known manner, power being supplied to the drive roller for
advancing the chart paper at a predetermined speed by a motor 24
shown in FIG. 5. Heat is supplied to the tip of recording pen 20 by
a heating element 26 indicated schematically in FIG. 4 and shown in
the circuit diagram of FIG. 5. 115 volt, 60 cycle power is supplied
to the wired chassis or main frame of the instrument 1 by a power
cord 28 and plug 30. The instrument circuitry consists of the wired
chassis and two plug in circuit boards having the circuits
illustrated in FIGS. 6 and 7. The main frame circuitry as shown in
FIG. 5 incorporates the pen drive motor 22, chart motor 24, pen
heating element 26, and associated controls and indicators together
with connectors for the circuit boards and sensors as hereinafter
set forth. The two plug in circuit boards as shown in FIGS. 6 and 7
contain substantially all of the associated control
electronics.
Strain gauge sensing devices 6 and 8 are preferably constructed as
ring shaped members from elastomer material. To this end silicone
elastomer loops as shown in FIG. 1 are filled with mercury to form
the strain gauges. Each strain gauge constitutes one leg of a
standard Wheatstone bridge circuit. Thus, as the strain gauges
expand and contract with variations in the circumference of the
anatomical member on which they are mounted, they change impedance.
This produces a varying output signal from the brige circuits in
which the strain gauges are connected. In FIG. 4 the two separate
bridge circuits 32 and 34 are illustrated schematically. These
bridge circuits are Wheatstone bridge circuits of well known design
and are therefore not shown in detail. The output signals from the
two bridge circuits are amplified and multiplexed into the single
channel strip chart recorder 14. The first and second stage
amplifiers 36 and 38 for strain gauge 6 are shown in FIGS. 4 and 6.
The same figures illustrate the first and second stage amplifiers
40 and 42 for strain gauge 8 and its bridge circuit 34. Each bridge
circuit has a zero line adjustment 44, 46, respectively, the
control knobs for which are shown on the front panel of control
cabinet 1 in FIG. 1. This adjustment compensates for differences
between individual strain gauges. Similarly, the gain of each of
the initial amplification stages is adjustable by variable
resistance controllers 48, 50, respectively as shown in FIGS. 4 and
6. The corresponding control knobs for these adjustments on the
instrument panel are designated by the same reference numerals in
FIG. 1. The input circuits from the two bridges are otherwise
identical except that the second amplifier stage 38 for bridge
circuit 32 and strain gauge sensor 6 adds a preset increment to the
signal that shows up as a positive displacement between the two
traces recorded by pen 20 on the strip chart recorder. The bias
signal for displacing the traces of the two input signals from each
other on recording paper 16 is introduced to terminal 52 of second
stage amplifier 38 by means of a voltage divider consisting of the
resistance elements shown at 54 and 55 in FIG. 6. The foregoing
adjustments are utilized as described below in calibrating the
instrument at the time of use.
Multiplexing of the separate diagnostic signals from the two strain
gauges and their respective bridge circuits 32, 34 to actuate pen
drive motor 22 is accomplished by switch means which preferably
takes the form of an analog switch 56 shown in FIGS. 4 and 7. The
output of analog switch 56 drives the pen motor 22 by way of a
unity gain amplifier 58 and a voltage-to-current converter 60. The
latter device is utilized because the pen motor is essentially a
current operated device. These components are shown schematically
in FIG. 4 and in the control circuit of FIG. 7. Converter 60
incorporates a positioning adjustment 62 used during factory
calibration to establish the basic recorder zero line. Unity gain
amplifier 58 incorporates provision for additional factory
calibration of pen deflection.
The main function control switch 64 is provided on the front of the
instrument panel. The rotary operation of the switch 64 in
combination with front and rear contact wafers 66, 68 illustrated
in FIG. 5 controls the calibration and recording operation of the
instrument. Switch positions 1 and 2 shown on the instrument panel
in FIG. 1 correspond to the TIP and BASE contact positions of the
switch illustrated in FIG. 5. With further reference to FIG. 5,
when switch 64 is in the TIP, BASE or BOTH positions, power
indicator light 70 should be lit. This indicator light is on the
bottom, front face of the instrument panel as illustrated in FIG.
1. A 15 volt regulated power supply is provided to the instrument
from a 115 volt power source by transformer 72. A second
transformer 74 provides the low voltage required for pen heater
26.
Analog switch 56 is part of the multiplexer. The recording and
monitoring instrument includes control means operative to condition
switch 56 to receive input signals alternately from the two sensing
devices 6 and 8, and their respective bridge circuits 32 and 34.
Analog switch 56 transmits these input signals alternately from
bridge circuits 32 and 34 to pen motor 22 through amplifier 58 and
converter 60. In response to these signals, pen motor 22 actuates
recording pen 20 so as to record two separate traces which reflect
and separate diagnostic signals received from sensing devices 6 and
8.
FIGS. 4 and 7 illustrate the control means utilized to cycle analog
switch 56 between the two input signals. The preferred control
device is a clock oscillator 76. This clock oscillator emits
control signals at predetermined time intervals which are inputted
to analog switch 56 through a frequency divider 78 so as to cycle
switch 56 between the two input signals at a desired frequency. As
noted above, these input signals are independently transmitted to
analog switch 56 from the output bridge circuits 32 and 34. As is
indicated in FIGS. 5, 6 and 7, the output signals from second stage
amplifiers 38 and 42 are transmitted from terminals points 80 and
84 to pin connectors 82 and 86 connected to input terminals 88 and
90 of analog switch 56. Referring now particularly to FIG. 7, when
control terminal 92 of analog switch 56 is high, input terminal 88
is connected to switch output terminal 94. When control terminal 92
is low, input terminal 90 is connected to output terminal 94 of
switch 56. Output terminal 94 drives pen motor 22 through
intermediate amplifier 58 and converter 60 as noted above. To this
end output terminals 96 and 98 are connected to pen motor 22 as
illustrated in FIGS. 7 and 5.
The state of analog switch output terminal 94 is determined by
frequency divider 78 connected between clock oscillator 76 and
analog switch 56. The output of clock oscillator 76 is a square
wave with a duty cycle of approximately 50 percent and a zero to
plus 15 volt excursion. The 15 volt half of the clock cycle turns
on transistor 100 which in turns toggles frequency divider 78.
Frequency divider 78 is a toggle flip-flop; its output changes
state on the negative going edge of the input pulse, hence the
output frequency is half the input frequency. When the output at
terminal 102 of frequency divider 78 is high, transistor 104 turns
on and drives control terminal 92 of analog switch 56 low. Control
terminal 92 remains low for a full oscillator clock cycle, then
switches high for a full clock cycle, and so on. In this manner
analog switch 56 is cyclically conditioned to alternately output
signals from the two bridge circuits 32 and 34 received through
connectors 82 and 86.
Since it is contemplated that the instrument of this invention will
find particular application for monitoring and recording diagnostic
signals over long time intervals on the order of eight hours or
more, chart drive motor 24 advances recording paper 16 at the
relatively slow speed of 20 centimeters per hour. This chart speed
assures that an eight hour record has adequate resolution but is of
manageable length. In order to avoid undesired marking and shading
between the two recorded traces as illustrated in FIGS. 2 and 3 at
such a relatively low chart speed, pen heater 26 is cycled off and
on so as to be de-energized during switching excursions of
recording pen 20 between the two traces. This is accomplished by
signal relaying means connected between clock oscillator 76 and pen
heater 26. As indicated in FIGS. 4 and 7, this signal relaying
means preferably takes the form of a silicone controlled rectifier
(SCR) 106. The output from SCR 106 is connected through terminal
connectors 108 and 110 with pen heater 26 as indicated in FIGS. 5
and 7. Each pulse of clock oscillator 76 triggers SCR 106 so that
pen heat turns off and on at the basic oscillator frequency. The 15
volt half of the clock cycle triggers SCR 106 and turns pen heat on
during the 15 volt half of the clock cycle. However, since frequecy
divider 78 operates as set forth above to trip analog switch 56
every other clock pulse to alternate the signal recording intervals
between the two sensors at half the clcok oscillator frequency, pen
heater 26 is turned off during the last half of each recording
interval. Thus, switching of pen 20 between traces by analog switch
56 occurs when the pen has has maximum opportunity to cool down.
This ensures that there is little or no pen marking between
traces.
Clock oscillator 76 and frequency divider 78 operate to cycle
analog switch 56 so as to switch between the two trace signals at a
frequency of less than once every one-half second. The switching
rate of pen 20 between traces by means of analog switch 56 is
preferably as slow as once every second. This has proven to be a
desirable frequency of pen switching between signal traces at the
preferred, relatively slow chart speed of 20 centimeters per hour.
Faster chart speeds may of course be used. However, for long
recording intervals of eight hours or more, as are encountered in
nocturnal penile tumescence monitoring, a chart speed of greater
than 50 centimeters per hour would generate an excessive amount of
chart paper for handling and study.
Because strain gauges 6 and 8 and the lead wire connections thereto
are rather delicate and easily broken, warning circuits are
provided to give visual indication if either of the strain gauges
is broken or becomes disconnected. Preferably, the visual
indicators are warning lights 112 and 114, these waring lights
being positioned on the front panel of control cabinet 1 as shown
in FIG. 1. With reference to FIGS. 4 and 6, it may be seen that the
warning lights 112 and 114 are wired in separate warning circuits.
The output of each of the second amplifier stages 38 and 42 for the
bridge circuits of the two strain gauges goes to separate
comparator controllers 116 and 118 for the warning lights as well
as to analog switch 56 through connection terminals 80 and 84.
Current to analog switch 56 as well as to the comparators 116 and
118 is limited by resistors 120 and 122. Voltage dividers 124, 126
and 128, 130 establish the set points of the two comparators 116
and 118, respectively. The output from these comparators is under
the control of a clock oscillator 138. When the voltage input to
either comparator 116 or 118 from either one of the bridge circuit
amplifiers 38 or 42 exceeds the set point the output terminal of
the corresponding comparator goes high and turns on the associated
transistor 132 or 134. When either transistor 132 or 134 conducts,
it connects output terminal 136 of clock oscillator 138 to
connector terminal 140 or 142. As FIG. 5 indicates, connector 142
goes to plus 15 volts through warning light 114 when function
switch 64 on the front panel of the instrument is in BASE or BOTH
position. Connector 140 goes to chassis ground by way of warning
light 112 when the selector or function switch 64 is in TIP or BOTH
position. The two warning lights comprise light emitting diodes
(LED) as indicated in FIG. 5. Thus, when connected into the
circuit, warning light 112 will turn on during the high half of the
clock cycle and warning light 114, when connected into the circuit,
will turn on during the low or ground half of the clock cycle. Any
type of mualfunction of either one of the strain gauges 6 or 8
resulting in a disruption of normal output voltage to comparators
116 or 118 will cause the respective warning light 112 or 114 to
start blinking.
Prior to utilization of the monitoring and recording instrument to
detect and record changes in the size of any anatomical member, the
two strain gauges must be calibrated. This is necessary to ensure
that the two trace signals are recorded on the appropriate zero
line at a desired displacement from each other. For this purpose a
calibration dummy of cylindrical shape having small and large
diameter ends is utilized. With the cable assemblies 10 and 12 from
the two strain gauges connected to the instrument through plug in
terminals 2 and 4, and power cord 28 plugged into a 115 volt
receptacle, calibration is carried out utilizing function switch 64
and calibration adjustments 44, 46, 48 and 50. For purposes of
nocturnal penile tumescence monitoring, one of the strain gauges is
designated the TIP gauge and the other is designated the BASE gauge
corresponding to the locations of the two strain gauges on the
subject's penis. The settings for function switch 6 have been
designated TIP and BASE in FIG. 5 corresponding to switch positions
1 and 2 in FIG. 1 for purposes of reference with respect to the
application of the instrument to nocturnal penile tumescence (NPT)
monitoring. With function switch 64 turned to the BASE or setting 2
position, the BASE gain adjustment knob 50 is set at approximately
the center of its travel position with the pointer at 12 o'clock.
The loop of the BASE gauge 8 is placed on the small diameter end of
the calibration dummy and the BASE zero line knob 46 is adjusted
for a pen deflection of predetermined value, such as, 10
millimeters. The loop of the same BASE gauge 8 is then placed on
the large diameter end of the calibration dummy and the BASE gain
adjustment knob 50 is adjusted for a pen deflection of a greater
magnitude, such as, 25 millimeters. The function switch 64 is then
turned to the TIP or setting 1 position and the other or TIP gauge
6 is calibrated in the same manner. However, the zero line and gain
adjustment knobs 44 and 48 for the other strain gauge are adjusted
so as to provide the predetermined displacement between the two
traces. This is accomplished by adjusting the zero line and
amplitude gain knobs 44 and 48 to provide a predetermined,
increased increment of pan deflection on the order of 10
millimeters, greater than the corresponding setting utilized for
the BASE gauge 8.
After the instrument has been calibrated in the foregoing manner an
NPT monitoring operation is undertaken by turning function switch
64 to the BOTH position to record both signal traces. The
calibrated strain gauges 6 and 8 are then positioned around the
penis of the subject as illustrated in FIG. 1. First, strain gauge
8 is positioned around the base of the penile shaft, then strain
gauge 6 is positioned around the tip of the penis directly behind
the glans. With function switch 64 in the BOTH position, monitoring
is undertaken for a predetermined period of time. Input from both
strain gauges will be recorded in the manner indicated in FIGS. 2
and 3. The TIP trace signals are recorded as trace 6a, and the BASE
signals are recorded as trace 8a corresponding to strain gauges 6
and 8, respectively. The NPT monitor measures minute variations in
penile size during the Rapid Eye Movement stages of sleep. The
cycling operation of analog switch 56 as described above sends
alternate drive signals from the two strain gauge sensors 6 and 8
to pen motor 22 causing it to move pen 20 so as to record two
separate traces indicative of variations in penile tumescence at
the tip and base of the penis. Measuring penile tumescence at both
the base and tip has proven to be particularly effective in
detecting all etiologies of impotence. Test results form the NPT
monitor utilized in this manner help the physician to gain a clear
and more object view of the part that organic causes play in male
erectile impotence and to better determine the appropriate course
of psychological or medical therapy. The signal tracings in FIG. 2
indicate significant tumescence activity. Organic impotence can be
ruled out in this case. The tracings shown in FIG. 3 indicate no
tumescence activity thereby strongly suggesting that impotence is
of an organic nature.
Sensing devices of various kinds other than strain gauges 6 and 8
could be used to sense and generate signals to the instrument. For
the particular applications of measuring changes in the size of
anatomical members, ring type strain gauges of the construction
disclosed herein have proven to be particularly effective. In
addition to NPT monitoring, such strain gauges may be used to
monitor changes in size of any member. It is contemplated that
various changes may be made in the size, shape and construction of
the various components and circuits of the recording instrument
disclosed herein without departing from the spirit and scope of the
invention as defined by the following claims.
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